An interesting paper from a Spanish group published in the Journal of Agricultural and Food Chemistry demonstrates that when rats are given grape extract it can counteract the detrimental effects normally associated with a “cafeteria” diet.
Rats were split into 3 groups and fed (1) a normal diet, (2) a normal diet supplemented with “cafeteria” food (bacon, biscuits with pâté, muffins, carrots, and milk with sugar) and (3) the same as (2) with the addition of grape seed procyanidin extract (GSPE).
Procyanidins have previously been shown to be able to improve glucose homeostasis.
The rats in group (2) exhibited a reduction in glucagon-like peptide-1 (GLP-1) which is involved in glucose homeostasis. This can lead to type II diabetes. The rats in group (3) given the same diet but supplemented with the GSPE did not have this reduction.
But if grape extract does not sound appealing to you procyanidins are also found in high quantities in apples, especially in the varieties Red delicious and Granny Smith according to Wikipedia.
An apple a day….